An annual event in late August that consists of racing decorated shopping carts. The one in Ann Arbor is among the few in the nation (see list here: http://en.wikipedia.org/wiki/Shopping_cart_race) Generally starts at the Fleetwood Diner. The race is a part of Punk Week.
Web Links
Gallery: http://jim.rees.org/culture/cart-race-2002.html A PDF detailing the event: http://www-personal.umich.edu/~lormand/agenda/0109/cartrace.pdf